fflash

go/cros-fflash

fflash is a tool to update a ChromiumOS device with a test image from gs:// (Google Cloud Storage).

Dependencies

Install depot_tools and you are all set! If you are a Chromium or ChromiumOS developer you are probably already set up.

Set up and Run

1. Make sure:

   • You can ssh ${dut_host} without typing a password.
   • Your DUT has access to the internet.

2. ~/chromiumos/src/platform/dev/contrib/fflash/fflash ${dut_host}
   

   Where ${dut_host} is the ssh target.

   The first time you invoke fflash, it might do some extra set up:

   • Build itself from source.
   • If prompted, use luci-auth to grant fflash access to Google Cloud Storage, and run again.

Alternative: Run without full ChromiumOS checkout

git clone https://chromium.googlesource.com/chromiumos/platform/dev-util
./dev-util/contrib/fflash/fflash

Usage examples

fflash ${dut_host}  # flash latest canary
fflash ${dut_host} --clobber-stateful=yes  # flash latest canary and clobber stateful
fflash ${dut_host} -R104  # flash latest R104
fflash ${dut_host} -R104-14911.0.0  # flash 104-14911.0.0
fflash ${dut_host} --board=cherry64 -R104  # flash latest R104 for board cherry64
fflash ${dut_host} --gs=gs://chromeos-image-archive/cherry-release/R104-14911.0.0  # flash specified gs:// directory
fflash ${dut_host} --gs=gs://chromeos-image-archive/volteer-cq/R118-15584.0.0-86601-8772438681633523617  # From CQ+1
fflash ${dut_host} --snapshot  # flash a recent snapshot build
fflash ${dut_host} --snapshot -R119  # flash a R119 snapshot build
fflash ${dut_host} --snapshot -R119-15634.0.0-88565-  # flash the snapshot 88565
fflash ${dut_host} --postsubmit  # flash a recent postsubmit build
fflash ${dut_host} --postsubmit -R115  # flash a R115 postsubmit build
fflash ${dut_host} --postsubmit -R115-15474.0.0-82578-  # flash the snapshot 82578
fflash ${dut_host} --dry-run  # print what would be flashed without actually flashing
fflash --help

What fflash does

• flashes the specified image, or latest image on the device
• clobbers stateful (optional, disabled by default)
• disables verified boot
• clears tpm owner (optional, disabled by default)
• reboot the device

it does not

• ask for sudo password
• flash minios

fflash is faster than cros flash if the connection between cros flash and the DUT is slow. cros flash proxies the gs://chromeos-image-archive images for the DUT (Google Cloud -> workstation -> DUT). fflash makes the DUT download the OS images directly, by granting the DUT a restricted access token to the Chrome OS release image directory (Google Cloud -> DUT).

Development

fflash is written in go and built with Bazel. Bazel handles the go toolchain.

You can invoke bazel through the tools/bazel launcher. If you obtained bazel through other channels, as long as it satisifies .bazelversion, it should also work.

Testing

Unit tests

tools/bazel test //...

Integration tests

tools/bazel run //cmd/integration-test ${dut_host}

Add go source / deps

Add the source normally and:

go get -u -d ./...
go mod tidy
tools/bazel run //:gazelle

to update the BUILD.bazel files.

Bazel emits a warning and a buildozer command to automatically fix the MODULE.bazel file if it is outdated.

Troubleshooting

partner_testing_rsa

If using crosfleet devices, you might need to copy https://chrome-internal.googlesource.com/chromeos/sshkeys/+/HEAD/partner_testing_rsa to ~/.ssh/partner_testing_rsa. Refer to b/260010430 for more information.

Bugs & Feedback

• Join the fflash-users Google Group (Googlers only).

• File a bug in our issue tracker.

Related tools

• cros flash is the officially supported tool to image ChromiumOS devices. It also allow flashing locally-built images.

• quick-provision is useful if your OS image is already on your ChromiumOS device.